1. Field of the Invention
The present invention relates to an information processing apparatus such as a host computer which controls a peripheral device such as a printer via a bi-directional interface, a control program used in the information processing apparatus and a memory medium for storing the control program.
2. Related Background Art
In a conventional situation where a printer is connected to a host computer for printing images, the host computer receives an operation status of the printer as well as error information which indicates a paper jam, a starvation of ink or toner, and the like, from the printer.
After that, the host computer displays the received operation status and error information on a display unit.
Therefore the host computer can notify a user of the status of the printer.
In a case where the printer does not execute a printing operation, the host computer receives information which indicates on-line or off-line status of the printer, a status of opening or closing of the printer cover, and the like, from the printer.
After that, the host computer displays the received operation status and error information on a display unit.
As mentioned above, the host computer transmits an interrogation command to the printer to demand the status of the printer from the printer, gets the status from the printer, and displays the status information transmitted from the printer on the display unit, by changing the status information to a character, figure and the like.
In this case, the host computer usually transmits the interrogation command to the printer at a fixed time interval which is set in advance.
In the above case, even if the printer is operating and the printer's status is changing only for a short time, the host computer transmits the interrogation command to the printer at each and every fixed time interval.
If the fixed time interval which is set in advance is longer than an interval in which the status of the printer changes, a time difference is generated between a status change of the printer and the host computer's discovery of the status change of the printer.
In addition, if the fixed time interval which is set in advance is decreased, even if the printer is not operating and the status changes of the printer are comparatively few, the host computer has to transmit the interrogation command to the printer too frequently.
This causes performance degradation in the host computer and printer.